Ian, thanks so much for the extra, detailed information about distances. As always, that is very helpful.
Have a nose through my Macro Gallery. I believe images 1 through to 152 are mostly shot with the Lastolite on, that is provided you're seeing the most recent shots first (should be the honey bee down through past the soldier fly. If not, let me know) -Gallery -->
http://ipc.smugmug.com/Close-Ups-Macro/Macro/4928508_h2LBHR#1474194621_gxJQvQZ.
I think I'm seeing the correct ones. You have a lot of beautiful shots, and not a few absolutely stunning ones. As preparation for potential discussions with the good wife about possibly getting yet another bit of photo equipment I sat her down to look at your smugmug images. Worked a treat.
While being duly impressed with all the fauna (and she is not very keen on, indeed in general is slightly repelled by, insects, spiders etc), she waxed especially lyrical about
this flower shot. She is a plantswoman, is incredibly sensitive to colour subtleties, knows the colours of many plants and prefers natural looking colours. The colours in that flower shot, she thought, were particularly realistic looking and delicately rendered. To say she liked the shot would be a bit of an understatement.
And as we discussed a number of your images it became increasingly clear that she has a very clear grasp of the potential of flash-illuminated images, and the downsides, and, critically from my perspective just now, the importance of getting that flash light nicely diffused.
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Lots to think about here. You are getting much better micro-details and micro-contrast than I can, and better freezing of motion, but a bit more "black background" effect, although not as frequently as I expected, and some light-source-shaped highlights, but mostly pretty unobtrusive and much/most of the time completely absent. Many of your images have an immediate and strong visual impact and "wow factor" for me.
My pictures in contrast seem lower key, lower impact, softer (in detail, contrast and colour, a palette a bit towards the pastel shades perhaps). And I'm not meaning to deprecate my images by saying this. I actually quite like some of the "softness" aspects in some of my images (but am borderline embarrassed by some other softness issues, wondering if I really would have done better to bin rather than post some of the shots. Trouble is, I've learnt that people respond differently to different aspects of a photo, and what can delight (or appal!) one person about an image can be totally unnoticed or if noticed then insignificant to someone else.)
I also seem to shoot less "macro" than you and more "close-up", and perhaps linked, a greater proportion of flowers. We have a common ground of whole-subject shots, from which you seem more often move in closer, while I more often move out further away. Possibly natural light is more appropriate the further out you move (and I'm sure flash becomes ever more essential as you move in really close).
Some trade-offs, objectives, preferences etc for me to mull over here, along with some usability issues. I am very drawn by the possibility of being able to produce images more like yours. I suspect the only way of testing its suitability for me is going to be to buy a Lastolite and try it for myself.
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I have wondered myself about side-mounting the flash, but because of the way my camera is mounted on a focus rail which is on a ball head my rather limited ability to understand and visualise mechanical devices has left me unable to envisage a working solution. All the side-mounts I have seen have been on brackets used for hand-held use, and given the way the camera is attached to the brackets I can't see how the bracket could then be attached to the focus rail - or some other combination.
I have become very comfortable with using the focus rail and tripod (even if I use neither in the "normal" way) and wouldn't want to give them up......Thinks....... Maybe have a "hand-held" setup, for use when I want to use flash as the main light source, with the flash side-mounted on a bracket. And keep the tripod + focus rail for available light (+ fill flash) use. Hmmm.... More to ponder.
I think before moving on to new equipment I should first do some more flash experiments with captures using my reflector and diffusers. And spend more time comparing and pondering on the differences between your (and others') images and mine, and from that what direction(s) I would like to move in. And think some more about potential mounting solutions.
Thanks so much for helping me to explore these issues.